1. Field of the Invention
This invention relates to an overall process of cooling, dust removal, tar removal and waste heat recovery of high temperature gas generated in coal gasification furnaces, and also to apparatuses employed in the above process.
2. Description of the Prior Art
According to one of processes for coal gasification, coal is gasified by reacting it with hydrogen, steam or the like at high temperatures and high pressures. Such gases generated from coal gasification furnaces have high temperatures of 800.degree. to 1000.degree. C. and contain dust such as undecomposed coal, ash, etc., byproduced tar, pitch, oil mist, etc.; hence in order to effectively utilize such gases, gas cooling, dust removal and tar removal are necessary, and at the time of cooling, it is also necessary to recover the waste heat by effective means.
The gas cooling has heretofore included two manners: usual tubular heat exchange and direct spouting of cooling medium. However, the tubular heat exchange employing shell-and-tube heat exchangers has drawbacks in that the tar contained in the cooled gas adheres onto the surface of heat transfer tubes, etc. and solidifies there to inhibit not only the heat transfer performance of the tubes, but also the gas flow function thereof. On the other hand, the latter cooling manner of directly spouting a lower temperature oil or the like into the gas is also uneconomical, since the sensible heat of the gas is scattered wastefully.